The objective of this project has been to build an expert system to analyze and interpret the Auditory Brainstem Response (ABR), an electrophysiological response of the human brainstem to acoustic stimuli. Expert reading of the ABR is essential in clinical decisions concerning retrocochlear disorders. We developed a rule-based expert system that performs neurodiagnostic interpretation of the auditory brainstem response. The system was developed on the IBM PC with the commercial system shell GURU and has been operational in the NIH Audiology Clinic for over one year. ABR interpretation strategies differ considerably among various clinics. Our system is a tool for rapidly modelling any ABR interpretive paradigm. Paradigms are easily added, modified, deleted, and selectively engaged at run time. Paradigm rules are boolean logic expressions containing discrete, continuous, and fuzzy variables representing ABR, subject, and stimulus parameters. The system models human ABR expertise in explicit representational form, handles routine cases well, reduce diagnostic errors of omission, and facilitates understanding of ABR clinical decision making. It can be used as a methodology for testing and validating any ABR interpretative strategy, a repository for meaningful ABR interpretative expertise, and a medium for sharing ABR knowledge.